Pressure indicator for fire extinguishers and the like



Oct. 2 1927. 1 6 6 968 E. A. LOUDER PRESSURE INDICATOR FOR FIRE EXT INGUISHERS AND THE LIKE Filed March 1920 ATTORNEY A. LOUDEB, OF 'NIJVJ YORK, ll.

15 SIG-N033, BY MEfiNE ASSIGNMENTS, TO

BOYCE AND VEEDIER C0. INC, OLE LGNG ISLAND GITY, NEW/V YQRK, A COR-POIBJL'IIC)N 03? NEW YORK.

PRESSURE INDICATUR FOR FIEE EXTINGQIISHERS AND THE LIKE.

Application filed. March 27, 1920.

This invention relates to improvements in indicators for vessels containing a liquid under pressure and has for its object to provide means for indicating pressure conditions existing within the vessel. The invention. more particularly relates to means for indicating the operative condition of fire eX- tinguishers of the type comprising a normally closed and tightly sealed vessel con taining an extinguishing liquid and a gas under pressure above the liquid, which is adapted to expand and forcibly expel the liquid from the vessel. when the discharge orifice thereof is opened. In apparatus of this type, it is necessary that the pressure of the gas should be maintained sufficiently high to insure the forcible expulsion of the extinguishing fluid, for if the pressure should fall below a predetermined amount, the liquid would. not be expelled from the vessel with sufficient force to be most effective in case of fire.

AS a fire extinguisher is an emergency apparatus, the importance of being able to ascertain instantly at any time the pressure condition existing within the same, is great, for while in a properly constructed extinguisher of the character referred to the gas will normally be retained at the proper operative pressure indefinitely, it is nevertheless true that in particular instances it may decrease through leakage or otherwise to such an extent that it will not be sufficient to effect the proper operation of the extinguisher. Consequently, the user thereof, on less he is warned of the fact that the fire extinguisher is not in proper condition, will be under the impression that it is ready for immediate use and will be misled into a false sense of security against fire.

The present invention provides a fire e:;- tinguisher having means for indicating to the user when the pressure of the gas is adequate and when ithas decreased to an extent such that the .appiratus will not operate elficiently. The invention also provides means by which it may be determined when the vessel in which the indicator is used is properly charged at the time of assembling; and enables an effective inspection of the product to be made at the factory or at any subsequent time.

In the accompanying drawings, which form a part of this specification, and in Serial No. 369,349.

which I have shown two preferred embodiments of the invention as illustrative of the principle thereof.

Figure 1 is a sectional View of a fire extinguisher constructed in accordance with and embodying my invention;

Figure 2 is a sectional view on an en larged scale, of the indicating member, and

Figure 3 is a front view of a modified form of indicating member, part being broken away.

Referring to the drawings, the fire extinguisher is shown as including a glass vessel 1., provided with a suitable head 2 which is hermetically sealed upon the vessel and serves as a fluid-tight closure thereforf In the particular construction illustrated, the head includes thermal fuse mechanism adapted to be released by heat so as to dis charge the contents of the extinguisher automatically on the occurrence of fire, and provision is also made for hand operation. T he vessel is filled nearly full with a fire extinguishing liquid, of any suitable composition, and the space within the vessel above the liquid is filled with a gas under pressure su'liicient to forcibly expel the liquid from the vessel when the fire extinguisher is operated to extinguish a fire. Usually, the liquid and used are of such a character that a certain proportion of the gas will be absorbed by or dissolved in the liquid, so that the liquid becomes charged. This will occur, for instance, if the liquid be carbon tetrachlorid, and the gas, air.

l ifithin the vessel 1 is a pressure indicating member 3, preferably formed of glass, and which, as shown in Figures 1 and 2, includes upper and lowerchambers l and 5, respectively. The upper chamber is closed and constitutes a permanently sealed air chamber or float which imparts a certain degree of buoyancy to the indicating member. The lower chamber 5, which is pref erably provided with a downwardly extending cylindrical portion 6, is provided adjacent its lower end with a small opening; 7 to permit the passage of the liquid in the vessel into, and out of the chamber 5. The chamber 5 also contains a quantity of gas, such as air, which will be compressed or expanded to vary its volume and therebyvary the buoyancy of the indicating; member, depending upon the quantity of extinguishing liquid within the chamber 5, which, in turn, depends upon the amount ofpressure exerted by the gas above the extinguishing liquid, as hereinafter set forth. Theindicating member is preferably weighted in any suitable manner, as by means of shot 8 positioned within the lower chamber 5, in order to obtain the proper degree of buoyancy and to obviate any tendency of the indicator to invert, so that this weight acting in conjunction with the float chamber lat the top of the indicator at all times, maintains the opening 7 submerged below the surface of the extinguishing liquid. By using shot 8 for weighting the indicating member, the spaces between the several shot afford ample passage for the free flow of the liquid into and from the chamber 5, and by introducing the right number of shot, any desired accuracy of calibration may be secured.

The chambers i and 5, and the amount of that when the pressure of the gas within the vessel 1 above the liquid is su'llicient to effect the proper operation of the apparatus, enough liquid will be forced through the opening 7 into the chamber 5 against the pressure of the air trapped therein to increase the weight of the indicating member 3 to an extent-such that it will sink to the lower end of the vessel, as shown in full lines in Figure 1, and as long as the gas pressure remains at or above its proper op erating value the indicating member will remain in its lower or submerged position. Should the gas pressure fall below its proper operating value, however, the pressure which it exertsupon the extinguishing liquid within the vessel will be decreased suillciently to permit the trapped air in the chamber 5 to expand and to expel therefrom enough liquid to effect an increase in the buoyancy ,of-

the indicatingmember, whereupon it will rise to the surface of the liquid, as indicated in'dotted line in Figure 1.

The use of the indicator in a receptacle containing a charged liquid under pressure, that is, a liquid having a certain amount of gas mixed or dissolved therein, renders the action of the indicator especially positive and reliabler In fact, with the construction shown, the indicator will work even if the lower chamber has become completely filled with the liquid so that at the normal pres sure there is no air pocket visible in the lower chamber. Under these circumstances, the indicator will nevertheless act because upon the reduction of pressure a certain amount of the dissolved gas is released'by the charged liquid and the gas released by the liquid within the lower chamber of the indicator will form an air bubble in the top of such chamber, thereby expelling a certain amount of the liquid and causing the indicator to rise when the pressure In the mam indicating member is clearly visible to the user of the fire extinguisher. It will, of course, be understood that the vessel 1 may be made of any other suitable transparentmaterial than glass or that it may be made mainly of non-transparent material and provided with a transparent portion through which the indicating membervmay be seen, or it may be constructed in any other manner permitting the position of the buoyant iember to be ascertained.

In Figure 3, there is shown a modified form of indicating member comprising a hollow cylindrical body portion 9 having a ransverse partition 10 therein forming upper and lower chambers 11 and 12 respec tively. At its lower end the body portion 9 is provided with the small opening 13 communicating with the chamber 12 to permit of the passage of the liquid into and out of said chamber. Upon its outer surface, the body portion is provided with a scale 14 in cluding numbers indicative of the pressure,

in convenient units such as pounds per.

square inch or the like, of the gas within the upper end of the vessel 1. The indicat mg member is weighted, as by means of shot 15 positioned withinthe chamber 12, to an extent such that it will always float within the liquid with the numeral of the scale, indicative of the gas pressure, showing just above the level of the liquid. Should the gas pressure fall, the air within the chamber 12 or released by the liquid in said chamber, will expand and expel some of the liquid from the chamber 12, as explained above,

whereupon the indicating member will rise, by means of its increased buoyancy until the numeral of the scale corresponding to the decreased pressure will appear above the surface of the liquid." As the user of the fire extinguisher will know the properpressure of the gas to insure eiiicient operation of the apparatus, he can tell at a glance whether or not the pressure has fallen to a point which will render the apparatusineffective.

WVhile I have illustrated and described two embodiments of my invention, it will be understood that various modifications may be made therein, and I do not, therefore, desire to limit myself to the specificconstructions set forth, nor do I desire to limit my- T-fi self to the invention as exemplified in fire extinguishers, but I intend to cover my invention broadly in whatever form its principle may be employed.

Having thus described my invention, I claim 1. In combination, a lire extinguisher containing liquid and gas under pressure, and an unconfined pressure indicating instrument in the liquid having an upper buoyant portion and a lower weighted portion where by said instrument is maintained right-sideup at all times by the buoyancy or the liquid without the aid oi extraneous supporting means.

In combination, a tire extinguisher containing liquid under pressure, and means for indicating the operative condition of the fire extinguisher comprising a submersible indicating member in the liquid responsive to the buoyancy thereof, said submersible member having an upper buoyant portion and a lower weighted portion, said portions bearing such relation to one another as to enable the buoyancy oi? said member to vary in accordance with the pressure in the extinguisher.

3. A fire-extinguisher comprising aclosed vessel, a fire-extinguishing liquid, a gas above the said liquid under a pressure normally greater than atmospheric, the said liquid when under pressure being charged with the said gas, and a pressure indicating means within the said vessel including a chamber normally filled with a liquid and a gas above the said liquid but under abnormal conditions filled only with liquid saturated with dissolved gas under the existing pressure, the said chamber having an opening communieating with the liquid in the said closed vessel, whereby the amount of liquid within the said chamber will be varied according to the solubility of the gas in the said liquid and cause the said indicating means to float to the surface, warning that the fire-extinguisher is inoperative upon a reduction of pressure below a predetermined value.

i. A device for inserting in liquids in closed vessels adapted to indicate changes of gas pressure to which the said liquids are subjected, comprising a plurality of glass chambers iiused to each other, the upper or" the said chambers being a hollow sphere, and the lower a hollow spherical portion having a tubular portion extending from its lower side the said tube bein oven so that fluid 7 b may enter free y, and the said lower chamber being filled with a plurality of shot adapted to keep the device with the tubular portion downward in the liquid and to facilitate calibrating the said device.

5. A. pressure indicating device of the character described, the upper part of which is a hollow glass bulb whose lower end is integral with a solid cylindrical portion oining the lower part thereto, said lower part comprising a hollow portlon drawmg out into a hollow open ended tube, and ballast contained in the said lower portion adapting the said device to remain in a predetermined position in a liquid and to facilitate calibration.

EARL A. LOUDER. 

